A common corrugated box used in packaging is the Regular Slotted Case (“RSC”). A conventional RSC has two major flaps running the length of the case (in the longer direction) and two minor flaps running the width of the case (in the shorter direction). When the flaps are folded to close the case, the major flaps overlie the minor flaps.
The conventional method for folding the major flaps is with stationary plows. As the case is conveyed toward a closing device, the stationary plows contact the major flaps and force them to a closed position. A disadvantage to this method is the friction produced between the plows and the flaps, which can be especially pronounced if the case is a heavy duty double walled case or if the case has been overfilled. This friction can distort the case causing an uneven fold. Another disadvantage is if the case is not perfectly centered between the two stationary plows (there is one plow per major flap), the case tends to skew because one flap begins to fold (and therefore be pulled back) by the plow before the other flap makes contact with the other plow.
As an alternative to stationary plows, a mechanism which uses a pair of major case flap closer bars connected to a pair of pneumatic cylinders can be used. This is a more positive way of closing the major flaps; however, there is still friction between the case and the folding bars. Once again, this becomes very obvious if the case has been overfilled. Also, this mechanism can be cost-prohibitive.
The conventional method to fold the front and rear minor flaps uses a stationary plow located at the upstream end of the machine to fold the front minor flap. Again, friction is undesirably created between the flap and the plow. The front minor flap is held closed with a stationary horizontal guide. The rear minor flap is then folded with an actuated mechanism located above the case. The rear minor flap must be folded before it reaches the stationary plow used to fold the front minor flap and before the major flaps are folded.
Thus, there is a need in the art for a positive method and device to fold the flaps of an RSC without producing excessive friction and without skewing the case.